A line-start reluctance motor is a single phase power alternating motor for performing constant speed motion. It is a combination type of an induction motor and a reluctance motor. The line-start reluctance motor includes a stator for forming a rotating magnetic field by alternating current applied to windings, and a rotor positioned in the stator and rotated by the rotating magnetic field formed by the stator. The line-start reluctance motor uses a rotary force generated when flux of the stator passes through the rotor and the rotor moves in a direction of decreasing reluctance (magnetic resistance). That is, in the start operation, the line-start reluctance motor starts to be rotated by using start torque generated by mutual operations of variations of the flux of the stator and current deserted in bars as in an induction motor, and after the start operation, the line-start reluctance motor is rotated in a constant speed by using reluctance torque making the flux of the stator flow through a core portion of the rotor.
As disclosed in U.S. Laid-Open Patent Application 3,862,446, a rotor for a two pole synchronous reluctance motor includes a core having a pair of effective oppositely disposed salient poles for improving initial start properties of the reluctance motor, a plurality of circumferentially spaced interconnected conductors in each salient pole portion adjacent to the periphery thereof forming main pole windings, the main conductors of each pole encompassing 90 mechanical degrees of the rotor core, flux barriers formed in and extending across the core between the main pole windings with the ends thereof circumferentially spaced from the main pole winding, and at least one additional secondary conductor located in the space between the ends of each main pole winding and each end of the flux barrier adjacent to the periphery of the core, the space between the ends of the main pole windings and the circumferentially nearest secondary conductor being greater than the space between any two adjacent main conductors, the conductors being connected together to form a squirrel.
According to U.S. Laid-Open Patent Application 6,604,134, a rotor assembly for a synchronous reluctance motor includes a shaft, a core having a plurality of shaped supports, the supports being configured, dimensioned and positioned to define a plurality of channels, the core being mounted on the shaft, a plurality of generally arcuate rotor sections, each of the rotor sections secured within a respective channel of the core, and a plurality of bands disposed circumferentially about the rotor sections for securing the rotor sections to the core.
In addition, as suggested in U.S. Laid-Open Patent Application 6,066,904, a mechanical device selected from a synchronous reluctance machine and a switched reluctance machine includes a rotor having a central axis, the rotor formed by a plurality of radial laminations, the laminations being stacked axially and being made of grain-oriented magnetic material having a direction of highest magnetic permeability, the direction of highest magnetic permeability of the magnetic material being parallel to a plane that bisects each of the laminations, each of the laminations having at least one pair of internal slots, at least one pair of internal slots being aligned in a direction at least generally parallel to the plane, and at least one pair of internal slots being symmetric about the plane.
As described above, the conventional rotors have a number of complicated elements, which consumes a lot of time and expenses during the production.
In addition, the conventional rotors require special elements (for example, conductors made of magnetic material).
The conventional arts do not provide maximum outputs and efficiency of the rotor based on a difference between flux density in a high permeable direction (for example, d axis) and flux density in a low permeable direction (for example, q axis).
Furthermore, the conventional arts do not provide shapes and alignments of bars for giving efficient output properties to the rotor by preventing magnetic saturation in the core.